Europium complexes with 1,2-bis(arylimino)acenaphthenes: A search for redox isomers

Article abstract of DOI:10.1007/s11172-015-0817-6

Reduction of 1,2-bis[(2,6-diisopropylphenyl)imino]acenaphthene (dpp-bian, 1) with metallic europium in 1,2-dimethoxyethane (dme) under anaerobic conditions gave a europium(II) complex with the acenaphthene-1,2-diimine dianion, (dpp-bian)Eu(dme)₂ (4), in high yield. Oxidation of complex 4 with triphenyltin chloride or 1,2-dibromostilbene afforded the corresponding halogen derivatives [(dpp-bian)Eu(μ-Cl)(dme)]₂ (5) and [(dpp-bian)Eu(μ-Br)(dme)]₂ (6). The molecular structures of complexes 4-6 were determined by X-ray diffraction. The magnetic moments of complexes 5 and 6 remain constant over a temperature range from 25 to 295 K; they are indicative of the presence of the europium(II) ion and the dpp-bian radical anion in both the complexes.

Full text of DOI:10.1007/s11172-015-0817-6

Russian Chemical Bulletin, International Edition, Vol. 64, No. 1, pp. 38—43, January, 2015
38
Europium complexes with 1,2ꢀbis(arylimino)acenaphthenes:
a search for redox isomers
I. L. Fedushkin,a A. A. Skatova,a D. S. Yambulatov,a A. V. Cherkasov,a and S. V. Demeshkob
aG. A. Razuvaev Institute of Organometallic Chemistry, Russian Academy of Sciences,
49 ul. Tropinina, 603950 Nizhny Novgorod, Russian Federation.
Fax: +7 (831) 462 7497. Eꢀmail: igorfed@iomc.ras.ru
bInstitute of Inorganic Chemistry, GeorgꢀAugust University,
4 Tammannstrasse, 37077 Göttingen, Germany.
Fax: + 49 (551) 39 33063. Eꢀmail: sdemesc@gwdg.de
Reduction of 1,2ꢀbis[(2,6ꢀdiisopropylphenyl)imino]acenaphthene (dppꢀbian, 1) with
metallic europium in 1,2ꢀdimethoxyethane (dme) under anaerobic conditions gave a europꢀ
ium(II) complex with the acenaphtheneꢀ1,2ꢀdiimine dianion, (dppꢀbian)Eu(dme)2 (4), in
high yield. Oxidation of complex 4 with triphenyltin chloride or 1,2ꢀdibromostilbene afforded
the corresponding halogen derivatives [(dppꢀbian)Eu(ꢀCl)(dme)]2 (5) and [(dppꢀbian)Euꢀ
(ꢀBr)(dme)]2 (6). The molecular structures of complexes 4—6 were determined by Xꢀray
diffraction. The magnetic moments of complexes 5 and 6 remain constant over a temperature
range from 25 to 295 K; they are indicative of the presence of the europium(II) ion and the
dppꢀbian radical anion in both the complexes.
Key words: europium, diimines, molecular structure, magnetic properties.
Scheme 1
Recently, we have observed for the first time redox
isomerism for rare earth elements with acenaphtheneꢀ
1,2ꢀdiimine derivatives of ytterbium as examples. Redox
isomerism in metal complexes is impossible unless they
contain two redoxꢀactive centers: a redoxꢀactive metal ion
and a redoxꢀactive ligand (e.g., orthoꢀbenzoquinone or
1,2ꢀdiimine). The phenomenon of redox isomerism is reꢀ
versible intramolecular electron transfer metal—ligand
under the action of external factors like a temperature
change. This phenomenon has been often observed in orꢀ
ganic derivatives of transition metals.1 The thermally inꢀ
duced electron transfer in a rareꢀearth metal complex in
solution, viz., in an ytterbium complex with 1,2ꢀbis[(2,6ꢀ
diisopropylphenyl)imino]acenaphthene (dppꢀbian, 1)
and 1,2ꢀdimethoxyethane (dme), [(dppꢀbian)Yb(ꢀBr)ꢀ
(dme)]2 (2), was first reported in 2009.2 The interconverꢀ
sions of the isomers occurred between 278 and 368 K. In
2012,3 we were the first to observe a true redox isomerizaꢀ
tion in the crystalline complex [(dppꢀbian)Yb(ꢀCl)ꢀ
(dme)]2 (3) (Scheme 1, Fig. 1).
In the latter case, the redox isomerization is accompaꢀ
nied by simultaneous changes in several characteristics of
complex 3: magnetic moment (Fig. 1), metal—ligand bond
lengths, unit cell parameters, and heat capacity. Up to
now, [(dppꢀbian)Yb(ꢀCl)(dme)]2 has been the only exꢀ
ample of a rareꢀearth metal complex showing redox isoꢀ
merism. Continuing a search for novel redox isomeric sysꢀ
tems among lanthanide complexes, we studied another
lanthanide, viz., europium, which also has two stable
oxidation states (+2 and +3). Here we describe the synꢀ
thesis, structures, and properties of new diimine derivatives
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 0038—0043, January, 2015.
1066ꢀ5285/15/6401ꢀ38 © 2015 Springer Science+Business Media, Inc.

Europium(II) complexes with diimines
Russ.Chem.Bull., Int.Ed., Vol. 64, No. 1, January, 2015
39

eff/
the halogenꢀcontaining reagent. This color change indiꢀ
cates the presence of the dppꢀbian radical anion in the
mixture. The target complexes [(dppꢀbian)Eu(ꢀCl)ꢀ
(dme)]2 (5) and [(dppꢀbian)Eu(ꢀBr)(dme)]2 (6) were isoꢀ
lated from benzene as red crystals. Since both the comꢀ
B
7.0
1
2
3
6.5
6.0
5.5
1
plexes are paramagnetic, H NMR spectroscopy cannot
be used to obtain analytical information on these derivaꢀ
tives. Nor can ESR spectroscopy be employed for detectꢀ
ing the dppꢀbian radical anion in complexes 5 and 6 beꢀ
cause both contain paramagnetic Eu ions. The different
reduction states of the diimine ligand in complex 4 and,
on the other hand, in complexes 5 and 6 emerge from their
IR spectra. The stretching vibrations of the single C—N
bond in the dppꢀbian dianion of complex 4 are manifested
as a band at 1300 cm–1, while the C—N bond with half
ꢀbonding between these atoms (hence, the bond order is
1.5) in the dppꢀbian radical anion of complexes 5 and 6
absorbs at 1520 and 1515 cm–1, respectively.
The transition of the dppꢀbian radical anion into the
dianion in complexes 2 and 3 upon cooling below 0 C is
accompanied by a color change from cherryꢀcolored to
blue. The latter color is characteristic of the dppꢀbian diꢀ
anion coordinated by a trivalent metal ion. As for comꢀ
plexes 5 and 6, their solutions do not change color even
upon cooling to a liquid nitrogen temperature. A DSC
study of the crystals of 5 in a range from 300 to 100 K (Fig. 2)
also revealed no abnormalities that could be attributed to
a redox isomerization accompanied by a phase transition.
The weak endothermic peak at 150—160 K is probably
associated with vanishing rotation of the Me groups of the
isopropyl substituents. The same effect is observed in free
dppꢀbian.
120
140
160
180
200 T/К
Fig. 1. Effective magnetic moment as a function of temperature
(200—100 K) for complex 3 in the crystalline state:3 (1) first
cycle, (2) second cycle, and (3) third cycle.
of europium: (dppꢀbian)Eu(dme)2 (4), [(dppꢀbian)Eu(ꢀCl)ꢀ
(dme)]2 (5), and [(dppꢀbian)Eu(ꢀBr)(dme)]2 (6).
Results and Discussion
Reduction of 1,2ꢀbis[(2,6ꢀdiisopropylphenyl)imino]ꢀ
acenaphthene (dppꢀbian, 1) with excess europium metal
(small lumps) in 1,2ꢀdimethoxyethane by heating under
anaerobic conditions gave the complex (dppꢀbian)ꢀ
Eu(dme)2 (4) in high yield (Scheme 2). During the reacꢀ
tion, the original bright orange solution turned brown,
which corresponds to the dppꢀbian dianion coordinated
with a divalent metal ion. Airꢀunstable complex 4 was
isolated from toluene as dark red orthorhombic crystals in
76% yield. With the aim of obtaining europium analogs of
ytterbium complexes 2 and 3, we oxidized complex 4 with
triphenyltin chloride and dibromostilbene (see Scheme 2).
In both reactions, the brown solution of 4 in dme turned
bright cherryꢀcolored immediately upon the addition of
In the case of redox isomerization, the transition
Eu2+Eu3+ should be accompanied by a drop in the magꢀ
netic moment from 11.24 to 4.95 B (with respect to two
Eu ions) because the eff values of Eu2+ and Eu3+ are 7.95
and 3.5 B, respectively.4 It can be seen in Fig. 3 that the
Scheme 2
i. Eu, DME (excess), reflux.
X = Cl (5), Br (6); Ox = Ph3SnCl (5), Ph(Br)CHCH(Br)Ph (6)
Ar is 2,6ꢀdiisopropylphenyl.

40
Russ.Chem.Bull., Int.Ed., Vol. 64, No. 1, January, 2015
Fedushkin et al.
Qsp/mW mg–1
–0.05
mental data using the Heisenberg—Dirac—van Vleck apꢀ
proximation with allowance for the Zeeman splitting:
exo
,
–0.10
–0.15
–0.20
–0.25
–0.30
–0.35
where J is the intramolecular Eu—Eu exchange coupling
constant.
The  values were corrected for temperatureꢀindepenꢀ
dent paramagnetism (TIP) by using the equation calc
=  + TIP. Theoretical curves are fitted best to the exꢀ
perimental data for the following equation parameters:
gdppꢀbian = 2.00, gEu = 1.95, JEuꢀEu = –0.05 cm–1, and
TIP = 1480•10–6 cm3 mol–1 for 5 and gdppꢀbian = 2.00,
gEu = 1.94, JEuꢀEu = –0.04 cm–1, and TIP =
= 1000•10–6 cm3 mol–1 for 6.
2
1
=
Molecular structures of complexes 4—6. Structures 4—6
were determined by Xꢀray diffraction and are shown in
Figs 4—6, respectively. Since intramolecular electron
transfers in crystalline samples are accompanied by changꢀ
es in the molecular bond lengths and, consequently, in the
crystal lattice parameters, we carried out Xꢀray diffraction
experiments at different temperatures to detect redox isoꢀ
merism in complexes 5 and 6: at 120 and 298 K for 5 and
at 120 and 170 K for 6. We found that both the unit cell
and molecular parameters of complexes 5 and 6 are
temperatureꢀindependent. Structure 4 was determined at
100 K. Crystallographic parameters and the data collecꢀ
tion and refinement statistics at low temperatures are sumꢀ
marized in Table 1; selected bond lengths and bond angles
are listed in Table 2.
150
170
190
T/К
Fig. 2. DSC curves (heating) for dppꢀbian (1) and complex 5 (2).
magnetic moments of complexes 5 and 6 provide unamꢀ
biguous evidence for the presence of Eu2+ ions over a wide
temperature range (295—2 K): at room temperature,

eff = 11.36 (5) and 11.28 B (6); these are very close to the
value calculated for a molecule containing two Eu2+ ions
(11.24 B). Some decrease in the magnetic moments beꢀ
low 25 K is probably due to weak intermolecular antiferroꢀ
magnetic exchange. The contribution of the unpaired
electrons localized on the dppꢀbian ligands to the total
magnetic moments of dimeric complexes 5 and 6 is small:
the magnetic moment calculated for the dimer containꢀ
ing two Eu2+ ions and two dppꢀbian radical anions is
11.51 B.
In structure 4 (Fig. 4), the sixꢀcoordinate environment
of the Eu atom is made up of four O atoms of two
dme molecules and two N atoms of the dppꢀbian ligand.
The Eu atom is appreciably out of the plane of the diꢀ
imine fragment: the dihedral angle between the
To evaluate the isotropic exchange between the euroꢀ
pium ions in complexes 5 and 6, we modeled the experiꢀ

eff/
B
13
5
6
12
11
10
9
5
6
C(2)
6
O(4)
C(1)
N(1)
5
O(3)
N(2)
Eu(1)
O(2)
O(1)
50
100
150
200
250
300 T/К
Fig. 3. Plots of eff (with respect to the dimers) vs. the temperaꢀ
ture for [(dppꢀbian)EuCl(dme)]2 (5) and [(dppꢀbian)EuBrꢀ
(dme)]2 (6): the circles and the curves refer to the experimental
and calculated data, respectively.
Fig. 4. Molecular structure 4 with atomic displacement ellipꢀ
soids (p = 50%). The hydrogen atoms are omitted.

Europium(II) complexes with diimines
Russ.Chem.Bull., Int.Ed., Vol. 64, No. 1, January, 2015
41
Table 1. Crystallographic parameters and the data collection and refinement statistics for complexes 4—6
Parameter
4•C7H8
5•2C6H6
6•2C6H6
Molecular formula
M
C51H68EuN2O4
925.03
C92H112Cl2Eu2N4O4
1712.67
C92H112Br2Eu2N4O4
1801.60
Crystal system
Space group
T/K
Orthorhombic
Pbca
Tricl–inic
P1
120(2)
Triclinic
P–1
100(2)
120(2)
a/Å
b/Å
c/Å
/deg
/deg
/deg
21.7278(7)
18.1487(6)
24.1760(8)
90
90
90
9533.4(5)
8
1.289
12.1878(2)
14.0814(3)
14.8548(3)
63.0289(18)
83.0457(15)
71.3756(16)
2152.28(8)
1
12.1266(10)
14.1253(12)
14.8549(13)
64.0510(10)
83.462(2)
71.344(2)
2166.8(3)
1
3
V/Å
Z
/g cm–3
1.321
1.556
1.381
2.406
/mm–1
1.359
F(000)
3864
884
920
Crystal dimensions/mm
 scan range/deg
Ranges of h, k, l
0.30×0.15× 0.15
1.93—26.00
–26  h  26
–22  k  22
–29  l  29
78822
0.30×0.30×0.20
2.96—27.00
–15  h  15
–17  k  17
–18  l  18
36742
0.38×0.28×0.09
1.77—28.00
–16  h  15
–18  k  18
–19  l  19
21494
Number of measured reflections
Number of unique reflections
Rint
9351
0.0382
9373
0.0261
10317
0.0135
Absorption correction (max/min)
(SADABS)
GOOF (F2)
0.8221/0.6859
1.0000/0.8218
0.8126/0.4616
1.020
1.055
1.046
R1/wR2 (I > 2(I))
R1/wR2 (for all reflections)
Residual electron
density (max/min), e Å
0.0402/0.0967
0.0524/0.1025
1.345/–0.936
0.0194/0.0472
0.0231/0.0486
0.633/–0.397
0.0257/0.0638
0.0305/0.0653
1.802/–0.498
–3
N(1)C(1)C(2)N(2) and N(1)Eu(1)N(2) planes is 11.6.
The Eu—N bond lengths in complex 4 are close to each
other (2.475(3) and 2.445(3) Å) but noticeably shorter
than those in the complex Cp*2Eu(Butꢀbian) (2.794(3)
and 2.768(3) Å)5 containing neutral acenaphtheneꢀ1,2ꢀ
diimine. At the same time, the Eu—N bond lengths in
structure 4 are similar to those in the complex Cp*2Eu(pꢀ
MeOꢀbian) (2.454(4) and 2.456(4) Å)5 containing the
acenaphtheneꢀ1,2ꢀdiimine radical anion. However, in
the absence of other anionic ligands, dppꢀbian cannot be
present in complex 4 as a radical anion because the metal
atom must be monovalent in this case, which is very unꢀ
likely. Each reduction state of the dppꢀbian ligand is known
to be characterized by its own structural "fingerprints".
When moving from the neutral ligand through the radical
anion to the dianion, the occupation of the LUMO of
dppꢀbian shortens the C(1)—C(2) bond and lengthens the
C(1)—N(1) and C(2)—N(2) bonds. The bond lengths of
the diimine fragment in complex 4 suggest its dianionic
state. For instance, the C(1)—N(1) and C(2)—N(2) bonds
(1.395(4) and 1.378(4) Å) are substantially longer than
those in free dppꢀbian (1.284(4) Å, both)6 as well as in the
complexes Cp*2Eu(Butꢀbian) (1.295(5) and 1.278(5) Å)5
and Cp*2Eu(pꢀMeOꢀbian) (1.345(6) and 1.334(7) Å).5 In
addition, the C—N bond lengths in the dppꢀbian ligand of
complex 4 are comparable with those in (dppꢀbian)ꢀ
Yb(dme)2 (1.392(3) and 1.379(3) Å).2
Table 2. Selected bond lengths d and bond angles  in comꢀ
plexes 4—6
Parameter
Bond
4
5
6
d/Å
C(1)—C(2)
N(1)—C(1)
N(2)—C(2)
Eu(1)—N(1)
Eu(1)—N(2)
Eu(1)—X(1)
Eu(1)—X(1)´
1.404(5)
1.395(4)
1.378(4)
2.475(3)
2.445(3)
—
1.448(2)
1.340(1)
1.330(1)
2.5704(9)
2.5894(9)
2.8704(3)
2.8890(3)
1.455(2)
1.329(2)
1.326(2)
2.566(1)
2.568(1)
3.0485(3)
3.0695(3)
—
Angle
/deg
N(1)—Eu(1)—N(2)
72.68(9)
66.60(3)
66.92(4)

42
Russ.Chem.Bull., Int.Ed., Vol. 64, No. 1, January, 2015
Fedushkin et al.
Complexes 5 (Fig. 5) and 6 (Fig. 6) are isostructural;
(1.340 Å),5 but are shorter than the C—N bonds (1.387 Å)
in structure 4 containing the dppꢀbian dianion.
both their crystallographic and molecular parameters are
similar, except for the metal—halogen bond lengths. Both
the complexes are centrosymmetric dimers with centers of
inversion at the midpoints of the segments connecting the
metal atoms. The coordination polyhedra of the Eu atoms
are somewhat distorted octahedra. The Eu—N bonds in
structures 5 (2.5704(9) and 2.5894(9) Å) and 6 (2.5658(12)
and 2.5683(12) Å) are similar in length to each other,
although being longer than those in complex 4 by more
than 0.1 Å. This lengthening of the metal—nitrogen bonds
in complexes 5 and 6 suggests that the europium cations
interact with the dppꢀbian radical anion in structures 5
and 6 more weakly than they interact with the dianion in
complex 4. The bond lengths in the diimine fragments of
the dppꢀbian ligands in complexes 5 and 6 correspond to
their radical anion character: the C—N bonds in 5 (1.335 Å)
and 6 (1.327 Å) are longer than those in the neutral bian
ligand in Cp*2Eu(Butꢀbian) (1.2870 Å),5 are virtually equal
to that in the bian radical anion in Cp*2Eu(pꢀMeOꢀbian)
To sum up, when complex 4 containing two reactive
sites (the dppꢀbian dianion and the Eu2+ ion) is treated
with oxidants, the diimine ligand becomes transformed
into the radical anion, while the divalent metal ion reꢀ
mains intact. The reverse reactivity was noted for a samarꢀ
ium analog of complex 4, viz., the complex (dppꢀbian)ꢀ
Sm(dme)2.7 In the presence of oxidants, it is the metal
that oxidizes first. In contrast to ytterbium complexes 2
and 3, complexes 5 and 6 show no thermally induced
electron transfer metal—ligand. Apparently, this is due to
a large potential difference between Eu2+/Eu3+ (–0.35 V)
and (dppꢀbian)2–/(dppꢀbian)– (–1.1 V).
Experimental
Complexes 4—6 are sensitive to oxygen and air moisture, so
all manipulations dealing with the synthesis, isolation, and idenꢀ
tification of these complexes were carried out in vacuo using the
O(2)
Cl(1)
C(1) N(1)
O(1)
O(1´)
Eu(1´)
C(2)
N(2)
C(2´)
N(2´)
Eu(1)
C(1´)
N(1´)
Cl(1´)
O(2´)
Fig. 5. Molecular structure 5 with atomic displacement ellipsoids (p = 50%). The hydrogen atoms are omitted.
O(2)
Br(1)
N(1)
C(1)
O(1)
O(1´)
Eu(1´)
C(2)
C(2´)
N(2)
N(2´)
Eu(1)
N(1´)
C(1´)
Br(1´)
O(2´)
Fig. 6. Molecular structure 6 with atomic displacement ellipsoids (p = 50%). The hydrogen atoms are omitted.

Europium(II) complexes with diimines
Russ.Chem.Bull., Int.Ed., Vol. 64, No. 1, January, 2015
43
Schlenk equipment. 1,2ꢀDimethoxyethane, toluene, and benꢀ
zene were dried with and stored over sodium benzophenone
ketyl and distilled from it immediately before use. IR spectra
(Nujol) were recorded on an FSMꢀ1201 FTIR spectrometer.
The magnetic susceptibilities  of polycrystalline samples were
measured on a MPMSꢀXLꢀ5 SQUID magnetometer (Quantum
Design) in a temperature range from 2 to 295 K (H = 5 kOe). The
paramagnetic contribution to the magnetic susceptibility was deꢀ
termined with allowance for the diamagnetic contribution  of
(in situ prepared from diimine 1 (0.5 g, 1 mmol) in DME). The
brown reaction mixture promptly turned bright cherryꢀcolored.
Crystallization from benzene gave complex 6 (0.49 g, 54%) as
red crystals, m.p. 265 C. Found (%): C, 61.12; H, 6.01.
C92H112Br2Eu2N4O4 (1801.60 g mol–1). Calculated (%): C, 61.34;
H, 6.27. IR (Nujol), /cm–1: 1671 m, 1643 m, 1590 m, 1515 s,
1311 w, 1251 m, 1185 s, 1073 s, 1031 s, 924 m, 877 m, 836 w,
821 w, 795 w, 777 w, 755 s, 720 w, 667 w, 601 w, 538 w.
Xꢀray diffraction study of complexes 4—6 was carried out on
Bruker Smart Apex (4, 6) and Agilent Xcalibur E diffractometers
(5) ( scan mode, MoꢀK radiation,  = 0.71073 Å, graphite
monochromator). The structures were solved by direct methods
and refined anisotropically (for all nonꢀhydrogen atoms) by the
leastꢀsquares method on F2hkl. The hydrogen atoms were locatꢀ
ed geometrically and refined isotropically using a riding model.
The calculations were performed with the SHELXTL9 and Crysꢀ
Alis Pro program packages.10 Absorption corrections were apꢀ
plied with the SADABS11 and ABSPACK (CrysAlis Pro) proꢀ
grams.10 The structures have been deposited with the Cambridge
Structural Database (CCDC Nos 1034227 (4), 1034228 (5),
and 1034229 (6)) and can be retrieved from the website
ccdc.cam.ac.uk/community/requestastructure/.
a sample estimated by the formula  = –0.5•M•10–6 cm3 mol–1
where M is the molar mass of the sample. Effective magnetic
moments were calculated by the formula eff = [3kT/(NA 2)]1/2
,
,
B
where NA is Avogadro´s number,  is the Bohr magneton, and k
B
is the Boltzmann constant. Magnetic exchange constants were
calculated with the DAVE program.8 The melting points of comꢀ
plexes 4—6 were determined in sealed capillaries. 1,2ꢀBis[(2,6ꢀ
diisopropylphenyl)imino]acenaphthene (dppꢀbian) was prepared
according to a known procedure.5 The yields of the reaction
products were calculated with respect to the amount of dppꢀbian
used (0.50 g, 1.0 mmol).
(1,2ꢀBis{(2,6ꢀdiisopropylphenyl)imino}acenaphthene)bisꢀ
(1,2ꢀdimethoxyethane)europium (4). Iodine (0.013 g, 0.05 mmol)
was added to excess europium metal (18 g, 118 mmol) in dme.
The resulting colorless solution of EuI2 was poured off the metal
by decantation. The metal was repeatedly washed with the solꢀ
vent. Then a solution of dppꢀbian (0.5 g, 1 mmol) in DME
(25 mL) was added to activated europium. The reaction mixture
was heated on a water bath (90 C) and vigorously shaken from
time to time. The originally orange reaction mixture turned redꢀ
brown. After 2 h, the resulting solution was poured off the excess
metal by decantation, filtered, and concentrated in vacuo. The
dark crystalline precipitate that formed was dissolved in hot tolꢀ
uene (20 mL). The resulting solution was concentrated under
reduced pressure and left for crystallization at room temperaꢀ
ture. The yield of complex 4 was 0.7 g (76%), dark red orthorꢀ
hombic crystals, m.p. 293 C. Found (%): C, 65.82; H, 6.89.
C51H68EuN2O4 (925.03 g mol–1). Calculated (%): C, 66.22;
H, 7.41. IR (Nujol), /cm–1: 1671 m, 1648 m, 1592 m, 1377 s,
1349 w, 1300 s, 1251 m, 1211 w, 1195 w, 1171 w, 1111 s, 1164 s,
1020 w, 982 w, 920 s, 854 s, 810 s, 753 vs, 725 w, 676 vs, 613 w,
594 w, 536 w, 512 w, 487 w.
Bis[1,2ꢀbis{(2,6ꢀdiisopropylphenyl)imino}acenaphthene]ꢀ
dichlorobis(1,2ꢀdimethoxyethane)dieuropium (5). Triphenyltin
chloride (0.39 g, 1.0 mmol) was added to a solution of complex 4
(in situ prepared from diimine 1 (0.5 g, 1 mmol) in DME). The
brown reaction mixture promptly turned bright cherryꢀcolored.
The solvent was replaced by benzene; the large colorless crystals
of hexaphenyldistannane that formed were filtered off. The benzꢀ
ene solution was concentrated to give complex 5 (0.35 g, 41%) as
red orthorhombic crystals, m.p. 280 C. Found (%): C, 64.12;
H, 6.31. C92H112Cl2Eu2N4O4 (1712.67 g mol–1). Calculated (%):
C, 64.52; H, 6.59. IR (Nujol), /cm–1: 1670 m, 1643 m, 1592 m,
1520 s, 1311 w, 1251 m, 1183 w, 1073 s, 1113 m, 1073 m, 1038 m,
924 s, 861 w, 835 w, 816 w, 788 m, 751 s, 723 s, 664 w, 601 w, 536 w.
Bis[1,2ꢀbis{(2,6ꢀdiisopropylphenyl)imino}acenaphthene]ꢀ
dibromobis(1,2ꢀdimethoxyethane)dieuropium (6). 1,2ꢀDibromoꢀ
stilbene (0.17 g, 0.5 mmol) was added to a solution of complex 4
This work was financially supported by the Russian
Foundation for Basic Research (Project No. 13ꢀ03ꢀ00713).
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Received November 17, 2014